doc: Add hint for Homebrew on Linux

[why]
If people want to use Homebrew on Linux to install the fonts they fail
following the documentation.

The reason is that Casks are not normally considered on Linux, because
they contain binary blobs for MacOS by definition. Well, the fonts are
indeed binaries, but could still be installed on any platform.

I can not find any expressive statement in the Homebrew or Homebrew-Cask
documentation, but trying on MacOS 15.3 and Ubuntu 24.04 showed this
different behavior.

[how]
Add back the `--cask` but only as addition for Linux, because
 - Main users of Homebrew are MacOS, and there it is deprecated
 - It might change on the Linux platform as well (for fonts?)

[note]
PR #1789
PR #1079

Reported-by: Pablo Sanchez @pablogrs
Signed-off-by: Fini Jastrow <ulf.fini.jastrow@desy.de>

readme.md

@@ -229,6 +229,8 @@ All fonts are available via [Homebrew Cask](https://github.com/Homebrew/homebrew
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Option 3: Unofficial Chocolatey or Scoop Repositories`
 
 > Option for **Windows** and wanting to use **Chocolatey** or **Scoop**.

readme_cn.md

@@ -258,6 +258,8 @@ _注_: **Requires cloning** the repo as of now
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `选项5: 克隆 Repo`
 
 > 适用于要使用 **完全控制**, **所有** 或者 **多数** 字体的情况，或者为Nerd Fonts的开发 **添一份力**的情况。

readme_es.md

@@ -249,6 +249,8 @@ Todas las fuentes están disponibles en [Homebrew Cask](https://github.com/Homeb
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Opción 5: Clonar el repo`
 
 > Es la mejor opción si quieres **control completo**, **todas** o **la mayoría** de las fuentes, o **contribuir** al desarrollo.

readme_fr.md

@@ -318,6 +318,8 @@ Toutes les polices sont disponibles via [Homebrew Cask](https://github.com/Homeb
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Option 5: Cloner le dépôt`
 
 > La meilleure option pour un **contrôle total**, de **toutes** ou **la plupart** des polices, ou **contribuer** au développement.

readme_hi.md

@@ -255,6 +255,8 @@ _ध्यान दें_:**क्लोनिंग की आवश्यक
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `विकल्प 5: रेपो का क्लोन बनाएं`
 
 > के लिए सबसे अच्छा विकल्प**पूर्ण नियंत्रण**,**सब**या**कुछ**फोंट के, या**योगदान**विकास के लिए।

readme_it.md

@@ -241,6 +241,8 @@ Tutti i font sono disponibili via la [Homebrew Cask](https://github.com/Homebrew
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Opzione 5: Clonare il Repo`
 
 > È l‘opzione migliore per avere il **controllo completo**, **tutti** o **la maggioranza** dei font, o per **contribuire** allo sviluppo.

readme_ja.md

@@ -237,6 +237,8 @@ macOS (OS X) では [Homebrew Cask](https://github.com/Homebrew/homebrew-cask)
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `その 5: リポジトリをクローンする`
 
 > **全てを管理したい**、または、**全て**のフォントが欲しい、または、開発に**貢献したい**場合に一番適した選択肢です。

readme_ko.md

@@ -238,6 +238,8 @@ macOS (OS X)의 [Homebrew Cask](https://github.com/Homebrew/homebrew-cask)를
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `옵션 5: 저장소 클론`
 
 > 폰트의 **모든** 또는 **대부분**을 **완전히 통제**하거나, 개발에 **기여**하기 위한 최고의 옵션.

readme_pl.md

@@ -313,6 +313,8 @@ Wszystkie czcionki są dostępne na [Homebrew Cask](https://github.com/Homebrew/
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Opcja 5: Klonowanie Repo`
 
 > Najlepsza opcja jeśli potrzebujesz **pełnej kontroli**, **wszystkie** lub **większość** fontów, lub dodajesz **kontrybucje** deweloperskie.

readme_pt-pt.md

@@ -237,6 +237,8 @@ Todos os tipos de letra estão disponíveis através de [Homebrew Cask](https://
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Opção 5: Dar clone ao repositório`
 
 > Melhor opção para obter **controlo total**, **total** ou **maioritário** dos tipos de letra, ou para **contribuir** para o desenvolvimento do projeto.

readme_ru.md

@@ -249,6 +249,8 @@ _Замечание_: **Необходимо клонировать** текущ
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Вариант 5: Клонировать Репозиторий`
 
 > Лучший выбор для **полного контроля всех** или **большинства** шрифтов, или для **помощи** в разработке.

readme_tw.md

@@ -257,6 +257,8 @@ _註_: **Requires cloning** the repo as of now
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `選項5: 複製 Repo`
 
 > 適用於要使用 **完全控制**, **所有** 或者 **多數** 字體的情況，或者為 Nerd Fonts 的開發 **盡一份力**的情況。

readme_uk.md

@@ -238,6 +238,8 @@ _Примітка_: **необхідне клонування** репозито
 brew install font-hack-nerd-font
 ```
 
+_On Linux you have to add `--cask` after `install`._
+
 ### `Варіант 5: Клонування репозиторію`
 
 > Найкращий варіант для **повного контролю**, **всіх** чи **майже всіх** шрифтів, чи **контриб'юції** до розробки.